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334

PRACTICAL ORGANIC CHEMISTRY

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(rKO-Hj3HLO). Then distil the liquid, vising a thermometer.
The alcohol, if volatile, will pass into the receiver, \vhilsl the
acid remains as the potassium salt in the vessel. The boiling
point will give some indication of the former. The distillate
should be fractionated and dehydrated with solid potassium
carbonate. Its -boiling-point and that of the bcnxoic ester is
then determined.

Glyccrides.—If the substance is a liquid fat or oil (/./•. non-
volatile, which decomposes on heating, turning brown and
evolving the smell of acrolein) then the hydrolysis is effected
with methyl-alcoholic potash as described. After hydrolysis, the
alcohol is driven off on the water-bath, the residue dissolved in
water, and the organic acid set free with hydrochloric acid. The
acid if solid is filtered, if liquid extracted with ether, or if soluble
and volatile (butyric acid) distilled and the remaining liquid
neutralised and evaporated to dryness. The ^lycerol is then
extracted with alcohol and the alcoholic solution evaporated on
the water-bath. The tests for glycerol may then !><• applied
(p. 106). The following is a table of common insoluble liquids
with their boiling-points and specific gravities. Where the
temperature is not indicated the specific gravity has been deter-
mined at o".

ORGANIC LIQUIDS, INSOLUULK IN WATKK.
(Containing C and II or C, II, and (>.)

J'tf't't il* f'flj/x —

'/ Ikx'im-      '   Present    in    I'etroi;  IViml-   f

^Heptane     I    cum' I'^r.and  Lij-roi.i     *|

;/-Oi:t;ine       J                                           \

I'ctroleuiu (l:unp oil).....

/-Amyleiu:..........

Benxep.e (p.  136).......

Toluene (p.  163).......

Klhyl henxene (p.   141)    ....
fl-Xylene...........

duinene (Iso]>ropyl ben/cue) .   .

Pseuclocumene........

Mesitylonr.........

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